The developmentally appropriate practices (DAP) guidelines proposed by the National Association for the Education of Young Children in 1987 have been widely taught in training programs for early childhood education and implemented in elementary school classrooms. The DAP standards have had a significant impact on the classroom experiences of millions of children. The proposed research builds on previous work examining the measurement of DAP and the effects of DAP on academic achievement. This research has three aims: 1) to examine the effects of DAP on the developmental trajectory of social skills and problem behavior; 2) to study the extent to which the school context relates to teacher use of DAP; and 3) to examine the combined effects of school context and DAP on trajectories of academic achievement and social skills. This study addresses methodological limitations of earlier research, using multilevel analyses appropriate to the nested nature of the data set and an observer measure of DAP with strong psychometric properties. The analyses proposed in this study make use of an existing data set that includes longitudinal data from over 4,000 former Head Start children and their peers. Data were collected in 30 states around the US including a diverse ethnic makeup. As in other studies evaluating the effects of DAP, results are limited by the fact that only those aspects of DAP that take place in the classroom on a regular basis are included. [unreadable] [unreadable]